Aṣálẹ kan jẹ ala-ilẹ nibiti ojoriro kekere ti waye ati, nitoribẹẹ, awọn ipo gbigbe ṣẹda awọn biomes alailẹgbẹ ati awọn eto ilolupo. Àìsí ewéko ń ṣí ojú ilẹ̀ tí kò ní ààbò hàn sí ìtanù. Nipa idamẹta ti ilẹ dada ti Earth jẹ ogbele tabi ologbele-ogbele. Eyi pẹlu pupọ julọ awọn agbegbe pola, nibiti ojoriro kekere ti waye, ati eyiti a ma n pe ni aginju pola nigbakan tabi “aginju tutu”. Awọn aginju ni a le pin nipasẹ iye ojoriro ti o ṣubu, nipasẹ iwọn otutu ti o bori, nipasẹ awọn idi ti igbẹ tabi nipa ipo agbegbe wọn.
Eyi ni awọn aginju 20 ti o tobi julọ ni agbaye.
| ipo | Aṣálẹ̀ | iru | Area |
| 1. | Aṣálẹ Antarctic | Pola yinyin ati tundra | 14,200,000 km2 (5,482,651 square mi) |
| 2. | Aṣálẹ Arctic | Pola yinyin ati tundra | 13,900,000 km2 (5,366,820 square mi) |
| 3. | Aṣálẹ Sahara | Subtropical | 9,200,000 km2 (3,552,140 square mi) |
| 4. | Omo ilu Osirelia nla | Subtropical | 2,700,000 km2 (1,042,476 square mi) |
| 5. | Aragbe Arabia | Subtropical | 2,330,000 km2 (899,618 square mi) |
| 6. | Aṣálẹ Gobi | Igba otutu tutu | 1,295,000 km2 (500,002 square mi) |
| 7. | Aṣálẹ Kalahari | Subtropical | 900,000 km2 (347,492 square mi) |
| 8. | Patagonia aginjù | Igba otutu tutu | 673,000 km2 (259,847 square mi) |
| 9. | Aṣálẹ Siria | Subtropical | 500,000 km2 (193,051 square mi) |
| 10. | Adagun Nla | Igba otutu tutu | 492,098 km2 (190,000 square mi) |
| 11. | Aṣálẹ Chihuahuan | Subtropical | 453,248 km2 (175,000 square mi) |
| 12. | Karakum aginjù | Igba otutu tutu | 350,000 km2 (135,136 square mi) |
| 13. | Colorado Plateau | Igba otutu tutu | 337,000 km2 (130,116 square mi) |
| 14. | Sonoran aginjù | Subtropical | 310,000 km2 (119,692 square mi) |
| 15. | Aṣálẹ Kyzylkum | Igba otutu tutu | 300,000 km2 (115,831 square mi) |
| 16. | Taklamakan aginjù | Igba otutu tutu | 270,000 km2 (104,248 square mi) |
| 17. | Ogangan aginju | Subtropical | 256,000 km2 (98,842 square mi) |
| 18. | Aginjù Thar | Subtropical | 238,254 km2 (91,990 square mi) |
| 19. | Aṣálẹ Puntland | Subtropical | 200,000 km2 (77,220 square mi) |
| 20. | Ustyurt Plateau | Aanu | 200,000 km2 (77,220 square mi) |
